Several types of bacterium have the capability of producing enzymes for cleaving proteins, the enzyme being commonly referred to as a proteinase. For most living microorganisms including bacteria, proteinases are an essential part of the metabolic apparatus. Hence many types of proteases have been isolated from cultures of known bacteria. The proteases isolated from a variety of bacterium can be classified according to the pH at which they express optimum activity and the essential amino acid at the active site in the protein digested by the enzyme. They can also be classified on the basis of any specific inhibition or co-factor requirement. Proteases can, therefore, be designated as acid, alkaline, or DFP-sensitive, neutral or metal chelator-sensitive and as thio-proteases. Such proteases may or may not be specific to the digestion and cleavage of specific proteins.
It is also known that a non-protease, neuraminidase is widely distributed in a variety of organisms, such as myxoviruses bacteria and animals. Recently, neuraminidase activity was detected in the culture fluid of Pasteurella haemolytica, Otulakowsky, G. L. et al, Infect. Immun., 42, 64-70 (1983). Neuraminidase from these various sources including Pasteurella haemolytica hydrolizes terminal sialic acids from glycoprotein and ganglioside oligosaccharides. Neuraminidase in cleaving such carbohydrates from glycoproteins does not in any way cleave the protein at any amino acid sites. However, Otulakowsky et al (supra) discovered that the supernatant from the culture of Pasteurella haemolytica not only had neuraminidase activity, but also had proteolytic enzyme activity in releasing sialo glycopeptides from glycoprotein. It was uncertain as to whether or not the enzyme activity was due to a new enzyme or previously known enzymes.